U.S. Pat. No. 6,178,085 shows a calculator with a lid hinged to an upper end of the calculator housing. When the calculator is in its stored configuration the lid lays flat over a display panel located in the front surface of the calculator. Upon releasing the lid from its stored position, the lid pivots rearwardly in a controlled, damped manner about a hinge connection between the lid and the calculator frame. The pivoting motion is driven by a torsion spring and damping drum arrangement located within a tubular bore within the hinge portion of the lid.
Des 426,849 to Lee shows a calculator, similar in outward appearance to the '085 patent. However, since it is a design patent the mechanical features of the opening mechanism is not shown.
Hollingsworth, U.S. Pat. No. 5,607,054 discloses a carrying case for a notebook computer having a front panel adapted to be folded rearwardly to form a stand to support the notebook computer in an inclined position.
Nelson, et al., U.S. Pat. No. 5,568,358 discloses a portable signal processing communications unit having a hinged cover which can be folded to form an inclined supporting structure for maintaining the unit in a upwardly tilted position during use when located on a horizontal supporting surface. Nelson includes a helical coil spring in a cylindrical bore in the lid but does not include a damping means
Loh, et al., U.S. Pat. No. 5,530,234 discloses a hand held calculator with a cover adapted to extend over the entire front surface of the calculator when the calculator is not in used. When the calculator is used, the cover is slid towards one end of the calculator along longitudinal side grooves in the calculator housing. The cover can then be rotated so it extends below the rear of the calculator to form a stand or support.
Narishima, et al., U.S. Pat. No. 4,703,160 shows a casing structure on a portable electronic appliance, such as a small hand held portable calculator, wherein portions of the casing are hinged to each other so they can be folded backwardly in order to form a supporting stand for maintaining the calculator or device in an inclined or tilted position during use on a support surface
Dynesen, U.S. Pat. No. 4,259,568 discloses a portable or pocket calculator having a casing structure including hinged cover. The cover portions are adapted to be folded rearwardly when the calculator is placed on a horizontal surface, providing a stand.
JP57-143626 to Murakami shows a calculator with a pivoting lid that serves as a cover as well as a stand. The helical coil spring in a cylindrical bore in the assembly appears to provide a friction damping function. However, it appears that the lid must be manually rotated about the hinge.
U.S. Pat. No. 4,390,289 to Houlihan show an elastomeric washer in a cylindrical bore along with a tightening screw. The lid can be manually rotated rearwardly up to about 350° to allow the device to stand on a surface at any desired angle to that surface.
U.S. Pat. No. 5,732,135 to Weadon et al—Shows a hinge configuration for a lid on a portable telephone. The housing has a pair of openings to receive movable pins mounted in a tubular portion of the lid. A coil spring in the tubular portion provides friction on the pins.
Many attempts been made to develop devices capable of properly moderating the movement of a lid, causing the lid, on release from its closed position, to be opened smoothly yet steadily and slowly. These devices typically make use of mechanical frictional force and incorporate rods in cylinders filled with oil.
U.S. Pat. No. 6,085,384 to Bivens shows a hinge damper comprising a blind cylindrical bore with a damping drum in that bore and a damping means within the cylindrical bore, that damping means being a viscous silicone oil or other viscous damping fluid or gel. The hinge arrangement is in a channel across the end of a lid or door that is pivotally attached to a stationary structure.
U.S. Pat. No. 3,118,167 shows a hinged structure with a cylinder formed integral with a longitudinal edge. A spindle is disposed coaxially within the bore of the cylinder. The space between the cylinder and the spindle is filled with a fluid-damping medium. A coil spring is located on the spindle so that it drives the hinge in one direction (closed), its torsional force being moderated by the fluid-damping medium.
U.S. Pat. No. 3,860,993 to Matuska is directed to a door opener that biases a door to an open position using a coiled spring with the opening action dampened by a viscous fluid. The device comprises a tubular portion extending along the longitudinal axis thereof with damping means in a cylindrical bore. The damping means comprising a helical coil spring in the bore, one end of the spring being secured against rotation to a bottom surface of the bore, and a damping drum connected to the opposite end of the spring. An enclosed space between the rotor and the inner wall of the cylinder is filled with a viscous silicone that damps the opening action of the spring.
U.S. Pat. No. 5,142,738 shows a still further example of a damped hinge. comprising a case with a rotatable cylinder therein, a high viscosity grease in a gap between the case and the rotatable cylinder A coil spring is mounted between the case and the rotatable cylinder.
U.S. Pat. No. 5,165,507 is yet another example of a hinge construction incorporating a cylindrical case, a damping drum, a coil driving spring and a viscous damping fluid.
U.S. Pat. No. 5,230,159 shows a calculator mounted to the surface of a tape measure. The calculator includes ribbed gripping surfaces 54, 56 along the outer edges of the housing.
In addition, numerous small electronic devices have been available for several years that include a hinged lid with a drive mechanism to open the lid once a latch is released. For example, Prodart of Hong Kong has offered various small calculators that include various pivoting portions, including covers and displays, which include a coil spring drive mechanism to effect opening. However, the damped drive is provided by a gear mechanism operatively attached to the lid. Several of these devices have a coil spring drive enclosed within a tubular portion at the hinged edge of the movable portion.